Inner spacer for double wall vent pipe



Aug. 2, 1955 S. EPSTEIN INNER SPACER FOR DOUBLE WALL VENT PIPE M m w R Zr SEB M PW aw w/ E] ELA L NE U BR

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s Hw Filed May 24, 1952 United States Patent Of 2,734,395 Patented Aug. 2, 1955 ice 2,714,395 INNER SPACER FOR DOUBLE WALL VENT PIPE Saul Epstein, Los Angeles, Calif. Application May 24, 1952, Serial No. 289,756 Claims. (Cl. 138-87) This invention relates to an inner spacer construction for a double wall vent pipe of a preferred sheet metal type.

It is intended by the instant construction to provide a spacer adapted to be inserted between the inner and outer concentrically arranged walls of a vent pipe of maximum rigidity of structure associated with utmost conservation of material, rigidity and adaptability.

It is also intended, as an object of the invention, to provide a desired spacer of the character described, permitting minimum engagement of the Walls thereof with the inner pipe to minimize heat conductivity while permitting a maximum flow or air circulation past said spacer in the interspace between the outer and inner pipes.

Yet another object of the invention is the provision of new and improved strengthened means at spaced bending stations along the subject spacer.

A further object of the invention is the provision of improved stable abutments of minimum extent, giving optimum staying qualities to the spacer as against axial dis placement thereof.

It is moreover among the objects of this invention to provide a new and improved spacer associated with a new and improved combination thereof with the walls of a preferred double wall vent pipe in which the same is particularly though not exclusively adapted to be used.

With these and other objects in view, the invention consists of the construction, arrangement and combination of the various parts of the device whereby the objects contemplated are attained, as hereinafter set forth, pointed out in the appended claims and illustrated in the accompanying drawings.

In the drawings:

Figure l is a vertical sectional view of the double wall vent pipe, parts being cut away showing the instant inner spacer embodying this invention, as taken on line 1-1 of Figure 2.

Figure 2 is a vertical sectional view 2--2 of Figure 1.

Figure 3 is a prespective view of the outer 'side of the spacer embodying this invention prior to bending the same for use.

Figure 4 is a similar view to Figure 3, but showing the opposite or inner side of said spacer, the ends being reversed from Figure 3.

Figure 5 is a perspective view of said spacer as bent in a condition for use.

Figure 6 is a plan View of blanks used for forming the spacer prior to folding or shaping thereof.

eferring more particularly to the drawings, there is shown by way of illustration a spacer, generally designated at 11), disposed between the walls 11 of an outer pipe and 12 of an inner pipe, collectively comprising a double wall vent pipe 13. Both the pipes 11 and 12 and the spacer are of preferred sheet metal such as aluminum.

The double wall vent pipe 13 which serves as the entaken as on a line vironment for the instant spacer is preferably formed in sections, each of which has a male end 114 and a female end 15, adapted to interfit with one another in any desired manner, as by means of interlocking ends 16 and 17 on the respective outer walls, and inter-engaging ends 18 and 19 on the respective inner walls at the interfitting ends of the adjacent sections.

The outer walls 11 are preferably formed with circumferential beads 20, and the inner walls are likewise preferably formed with annular beads 21, adapted to retain the spacer 10 against axial displacement within the inner space 22 between said inner and outer pipes.

The spacer 1G is so formed that a plurality of blanks 23 may be cut from a continuous sheet of material without waste. This may be seen most clearly in Figure 6.

Said blank is formed with triangles or the like 24 at spaced intervals therealong corresponding to the bending stations whereby the spacer is bent segmentally in its completed form for insertion into the interspace 22 pereferably during the manufacture of the double wall pipe, as will be noted.

The spacer is generally L-shaped in cross-section, but is formed between said fold stations with elongate, dishshaped, preferably substantially arcuate reinforcing dimples at the juncture between the vertical arms 25 and the horizontal arms 26 of the L, said dimples being designated at 27, and being directed inwardly preferably for a distance approximately equalling the amount of outward projection of the horizontal arms of the respective dimples beyond the plane of the vertical arms, as may be seen most clearly in Figure 2.

The dimples 27 thereby also preferably have as their lower wall the continuous lower arms 26, whose outer edges 30 are, in the dimpling operation, drawn into respectively areuate shapes, as seen in top view (Figure 2), substantially conforming and paralleling the convexity of the inner edges 31 of the dimples 27. Said lower or horizontal arms 26 thereby provide reinforcing flanges for each segment 32 of the spacer to prevent radial distortion of said segments or said spacer occasioned by radially directed stresses against the pipes 11 and 12.

At their ends, the dimples taper in depth towards the bending stations at 33, said tapers being denoted at 34,

so that the dimples preferably terminate in longitudinal spaced relationship to one another. The strength of the dimples is therefore distributed over the segments 32, and

i the triangular stations 24 defining 2.

their adjacent termini are at lines of said bending at 33 and 24.

As may be seen most clearly in Figures 1 and 5, the bend stations are distributed over a substantial portion of somewhat flared area are normally slightly weakness permitting of bending, so that the tips 35 spaced inwardly from the walls of the outer pipe 11, although being in close proximity to such walls. If desired, by bending the spacer along distinct non-flared lines, the spacer can make line contacts with the outer wall 11 of the pipe axially thereof to resist any possible misalignment of the spacer circumferentially within said interspace 22. n

The inwardly directed tips 35 serve to emphasize another feature of this invention, to wit: the structure of the spacer is such that only minimum areas of contact are provided between the spacer and inner and outer walls 11 and 12, thereby minimizing undesired heat conductivity between the inner and outer pipes 11 and 12. Thus, when the spacer is shaped in its final form, cutouts 36, formed by triangular stations 24 of an adjacent blank 23 and likewise serving to define the fold lines of the spacer, substantially conform, as shown most clearly in Figure 2, to the curve of the inside of the wall of the outer pipe 11, making, therefore, generally line contact therewith at the spaced positions around the pipe, but leaving passages 37 between the spacer and the outer pipe walls and other passages 38 between the spacer and the inner pipe 12. Such passages encourage a desired air circulation within the interspace 22 longitudinally of the pipe to maintain a uniform temperature therein, and as where the outer pipe wall 14 is perforated, permits the circulation of outside air within the interspace past the spacer.

The ends 40 and 41 of the spacer respectively comprise a terminal tab normally bendable, as along a line 42, and provided with an eyelet 43. The end tab 40 is formed with a tongue 44 having an offset 45 formed therein, said offset being adapted, when the tongue 44 is positioned within the raised eye 43 for securing the ends together to prevent withdrawal of the tongue from the eye.

The tongue and eye form mutual abutments to prevent collapse of the spacer to a smaller diameter than that intended, and so facilitate its assembly and preserve its shape during telescoping of the two pipes 11 and 12. During such telescoping the spacer is formed as shown in Figure 5, with the two ends thereof inter-engaged, and the same is either inserted into the outer pipe 11 or positioned under the circumferential groove 21 formed in the inner pipe. The inner pipe is then slipped down within the outer pipe and the corresponding ends thereof at 14, preferably secured together as by riveting or welding at spaced indentations 45 therearound.

One end 14 of the double wall pipe is thus firmly secured together in spaced relationship by said indentations, While the other end of each double Wall pipe section is held in spaced coaxial relationship by the spacer 10.

The spacer constructed as above is sufficiently rigid that the pipe walls 11 and 12 may be deformed before the spacer will yield its preformed shape. However, while the individual segments 32 of the spacer are rigid, the total spacer will yield at the bend stations 33-34 when the double wall pipe is forcibly compressed into an oval shape, as is sometimes occasioned during a tight fit between too close walls of a building. The stilfness of the sections 32 of the spacer, even in such use, however, insures adequate optimum spacing between the inner and outer pipe walls, and the instant spacer does not collapse more at the compressed portions of the double wall pipe than at the bulged wall portions during such compression, in the undesirable manner of prior art spacers.

As heretofore noted, the instant spacer is preferably formed from aluminum, and it has been found that aluminum of .018 of an inch thickness is satisfactory for such purpose. Likewise, the total width of the aluminum blanks 23 has been found adequate at only five-eighths of an inch from the top edge 46 to the bottom edge 30 thereof. Moreover, as formed, the instant spacer construction provides an increased resistance to bending of the sections 32 many times that of any known prior art construction or comparable material.

Although I have herein shown and described my invention in what Ihave conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of my invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent structures and devices.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In combination with a double-wall vent pipe comprising an inner sheet metal pipe wall and an outer coaxial sheet metal pipe wall radially spaced from said outer wall, one of said walls having a first interval circumferential head formed therein and having a second interval circumferential bead formed therein in axially spaced relation to said first bead, an annular spacer disposed between said walls and said beads and adapted to abut against said beads to restrain the spacer against axial displacement relative to said pipe, said spacer comprising a sheet metal strip having a generally L-shaped crosssectional shape and having circumferentially elongate reinforcing dimples spaced along the vertical wall of the L, defining areas of relative weakness therebetween, said dimples having a side wall continuous and in the same plane as the horizontal arm of the L.

2. A spacer comprising a sheet metal strip adapted to be inserted between the inner and outer walls of a vent pipe, said spacer having a generally L-shaped crosssectional shape and having circumferentially elongate reinforcing dimples spaced along the vertical wall of the L, defining areas of relative weakness therebetween, said dimples having a side wall continuous and in the same plane as the horizontal arm of the L, the horizontal arm of said spacer being formed with notches laterally adjacent the said areas of relative weakness whereby the spacer is bendable between the dimples defining individual dimple-formed segments, said vertical arm of said spacer having vertically extending portions making said vertical spacer arm of greater Width opposite from said notches to reinforce said spacers at the areas of relative weakness.

3. A spacer comprising a sheet metal strip adapted to be inserted between the inner and outer walls of a vent pipe, said spacer having a generally L-shaped crosssectional shape and having circumferentially elongate reinforcing dimples spaced along the vertical wall of the L, defining areas of relative weakness therebetween, said dimples having a side wall continuous and in the same plane as the horizontal arm of the L, the horizontal arm of said spacer being formed with notches laterally adjacent the said areas of relative weakness whereby the spacer is bendable between the dimples defining individual dimple-formed segments, said vertical arm of said spacer having vertically extending portions making said vertical spacer arm of greater width opposite from said notches to reinforce said spacers at the areas of relative weakness, said notches having a shape matching said respective vertically extending portions of the vertical arm in the unbent condition of the spacer, said spacer being adapted to be bent at positions between said dimples for a press fit between the inner and outer walls of a double-wall vent pipe.

4. A circumferential spacer of generally L-shaped cross-section for disposition between the inner and outer walls of a vent pipe, said spacer having reinforcing dimples along the vertical wall of the L having a side wall continuous with the horizontal wall of the L and notches along the horizontal wall of the L between the dimples for bending the spacer circumferentially.

5. In combination with a double-wall vent pipe, a circumferential spacer according to claim 4 disposed between the inner and outer walls of the. pipe and positioning means on the walls of the vent pipe to retain the spacer against axial displacement.

References Cited in the file of this patent UNITED STATES PATENTS 369,169 Dewey Aug. 30, 1887 2,076,210 Stadtfeld Apr. 6, 1937 2,113,083 Height Apr. 5, 1938 2,512,116 Siebels June 20, 1950 

